Pedaling torque and power measuring device for a bicycle

Abstract

A torque and power measuring device corresponding to the non-drive side cyclist leg, comprising a hollow shaft connecting the two bicycle crank arms with strain sensors arranged in the shaft surface. These sensors are connected to an electronic control unit housed inside the shaft, to which are also connected other different sensors to measure a plurality of interesting quantities (pedaling cadence, crank arm angular position . . . ). This electronic control unit picks the sensor signals up, stores them and performs pre-programmed software operations to later wirelessly output the result signals towards a receiving device for analysis and/or storage them, by means of an antenna located outside the shaft and anchored to the outer surface of the jointed crank arm with the shaft.

The invention claimed is: 
     
       1. A torque and power measuring device located on a non-drive side cyclist leg, comprising:
 a hollow shaft configured in one piece, which connects a first bicycle crank arm and a second bicycle crank arm, wherein the first crank arm is a jointed crank arm relative to a shaft, and the second crank arm is a detachable crank arm; 
 at least one strain sensor disposed on a surface of said shaft which measures deformation caused by torque on the shaft; 
 at least one angular position sensor or rotation sensor of the shaft; 
 a support member housed inside the shaft and moving jointly with it, which supports an electronic control unit configured to receive input signals at least from the abovementioned strain and positioning sensors, to store data, to perform pre-programmed calculation operations with them and to output result signals; 
 a power supply unit housed inside a support member; 
 a radiofrequency antenna, located outside the shaft anchored to an outer surface of the jointed crank arm in its corresponding assembly area with the shaft, and wiring connected to the electronic control unit which wirelessly sends the result signals to a signal receiving device; 
 characterized in that the jointed crank arm is provided with an opening located in the assembly crank end with the shaft, through which antenna wiring passes to outside the shaft. 
 
     
     
       2. A torque and power measuring device according to  claim 1 , characterized in that the shaft is provided with a groove located at its assembly section with the jointed crank arm, to let the antenna wiring pass by from inside the shaft towards said opening of the jointed crank arm. 
     
     
       3. A torque and power measuring device according to  claim 2 , characterized in that said strain sensor is arranged on an outer surface of the shaft which comprises at least one opening to let the strain sensor wiring pass by to connect it with the electronic control unit. 
     
     
       4. A torque and power measuring device according to  claim 3 , characterized in that said strain sensor comprises a pair of strain gauges arranged in +/−45° in relation to the shaft generating line, in a Wheatstone bridge configuration. 
     
     
       5. A torque and power measuring device according to  claim 4 , characterized in comprising at least one pair of strain sensors diametrically opposite located. 
     
     
       6. A torque and power measuring device according to  claim 3 , characterized in that the shaft is provided with at least one recess made on its outer surface wherein at least one strain sensor is housed. 
     
     
       7. A torque and power measuring device according to  claim 6 , characterized by further comprising a removable closure member located in the end shaft corresponding to the jointed crank arm to seal a power supply unit. 
     
     
       8. A torque and power measuring device according to  claim 7 , characterized in that said angular position sensor comprises an accelerometer at least bi-axial, located on the axis of the shaft and a magnetic sensor at least bi-axial, so that the angular position of the jointed crank arm is known at all times. 
     
     
       9. A torque and power measuring device according to  claim 8 , characterized in that said accelerometer is used to measure the angular position of the crank arm with time, under zero bicycle speed conditions. 
     
     
       10. A torque and power measuring device according to  claim 8 , characterized in that said magnetic sensor is used to measure a time-dependent angular position of the crank arms under any bicycle speed conditions, using a magnet fixed on any near position of a bicycle frame. 
     
     
       11. A torque and power measuring device according to  claim 8 , characterized in that said magnetic sensor together with a magnet located on a rim of a bicycle rear wheel, is used to measure the time taken for the wheel to make one complete revolution, to compute both instantaneous bicycle speed and cyclist gear ratio at all times, as a result of a ratio between the rear wheel revolutions and the crank arm revolutions. 
     
     
       12. A torque and power measuring device according to  claim 7 , characterized in that said angular position sensor comprises an accelerometer at least bi-axial, located on the axis of the shaft and a gyroscope so that the angular position of the jointed crank arm is known at all times. 
     
     
       13. A torque and power measuring device according to  claim 12 , characterized in that said accelerometer is used to measure a time period in which the crank arm makes a complete revolution and therefore a rotation cadence of the jointed crank arm. 
     
     
       14. A torque and power measuring device according to  claim 7 , characterized in that said angular position sensor comprises a magnetic sensor and a gyroscope to know at any time the angular position and velocity of the jointed crank arm. 
     
     
       15. A torque and power measuring device according to  claim 1 , wherein the jointed crank arm is located on a bicycle drive-side, and further comprising at least one strain sensor which measures a deformation caused by a bending moment of said jointed crank arm in a plane of pedaling, and being also connected to the electronic control unit in order to independently measure as well torque and power exerted by the drive side cyclist leg.